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Sniffing Out Trouble

The importance of the sense of smell is not always as obvious as the nose on one's face. Despite the fact that there were seven noses aboard the space shuttle Discovery four years ago in the form of the human crew, the E-Nose had the ability to sniff out what they could not. Although it may not look like your average sniffer, JPL's shoebox-size electronic nose, or E-Nose, is based on the same mechanisms that allow humans to detect and differentiate smells.

While astronauts, including John Glenn, were busy with the mission's objectives, the E-Nose was tucked away in a corner of the crew deck, quietly monitoring the air they breathed. Since certain gases in large concentrations are toxic to humans (like acetone and hydrazine - a component of rocket fuel), the E-Nose was a welcome addition to the already cramped workspace.

Fortunately for astronauts on that mission, none of the 10 contaminants the E-Nose was trained to smell were detected, according to JPL's Dr. Amy Ryan, principal investigator for the E-Nose. Tests conducted on samples from the flight (brought back in canisters) confirmed what the E-Nose concluded.

The E-Nose contains 32 thin polymer carbon composite film sensors on a very small chip. These different polymers or sensors expand or contract depending on the elements in the air. The reaction of the individual polymers creates a pattern, or fingerprint, which scientists can evaluate using JPL-written software. Like the human brain, the E-Nose is trained to recognize these patterns and smells.

The E-Nose has many potential uses down here on the ground, too. JPL scientists hope that the E-Nose may one day aid in the early detection of fires. Its commercial and medical uses might include detecting unexploded land mines, smelling chemical spills and uncovering diseases.

The E-Nose's abilities might also expand to the food and agriculture industries. It can detect certain ingredients in food and sense the ripeness of fruit to ensure harvesting at the ideal time. Although this smart snout cannot choose its favorite soda, it can tell the difference between the top two brands.

Environmental threats like smog are very familiar to southern Californians. However, an environmental problem of an entirely different sort may provide another job for the E-Nose. In states with a booming swine industry, residents are suffering from an aroma nuisance wafting through the air courtesy of an abundance of pig farms. Electronic noses will prove their mettle by smelling what neighbors would rather not. Early detection of the offensive odors will allow pig farmers to clean up before the offensive odors spread. The technology could also help public works departments detect sewer smells.

Getting a Nose Job

JPL researchers are now busy creating a smaller version of the E-Nose, with expanded capabilities. The new E-Nose will be significantly smaller and lighter. It will shrink from 2000 cubic centimeters (about 120 cubic inches) to 760 cubic centimeters (about 46 cubic inches) and its weight from 1.4 kilograms (about 3 pounds) down to approximately 0.70 kilograms (about 1.5 pounds). It will be controlled with either a Personal Digital Assistant or laptop with real-time software that transmits data within 15 minutes of an "event," or detection.

The success of the E-Nose hundreds of miles away on the Space Shuttle paved the way for countless uses in space and on Earth. Like many budding technologies, the new version will be scaled down and more aesthetically pleasing than its parent. Plastic surgeons beware!